Field of the Invention and Related Art Statement
This invention relates to an electronic endoscope apparatus provided with a means of detecting the movement of an imaged object image.
Generally the movement of an image within such picture as a TV picture is largely divided into a movement by the movement of an object within the picture and a uniform movement of an entire image by the parallel movement of the camera. In the case of transmitting, for example, such image, for the purpose of efficiently utilizing the transmitting path, the band of the image is compressed.
A transmitting method wherein the part of a local movement of an object within an image is processed as a movement region, the movement in one direction of the entire image is processed as a still region by detecting a movement vector and a band compression stronger than in the still region is applied to the movement region is known and many movement detecting circuits have been devised and utilized.
However, in some case, depending on the use of the imaging apparatus, the size of the movement quantity may be positively detected without distinguishing the local movement of such image and the movement in one direction of the entire image from each other. For such use, there are not only a crime preventing apparatus, such adapted Y/C separating apparatus as is shown in the publication of a Japanese patent application laid open No. 106288/1985 and sequential scanning converting apparatus but also an apparatus displaying as a still picture output of an electronic endoscope apparatus used for a medical instrument an object image in a state as still as possible in a high resolution (that is to say, in a frame sequential imaging system, a frame freezing little in the color lag and image lag is made and, in a simultaneous imaging system, a frame freezing little in the field flicker is made).
By the way, in the above mentioned sequential imaging system, the object sequentially illuminated by illuminating lights of different wavelength regions is sequentially imaged and the images are then composited to be a color image. In the simultaneous system, a color imaging (image) is made by once imaging by an imaging means using color filters under a white color illumination.
By an ordinary movement detecting means, an accumulated value in corresponding pixels between generally different frames is determined and a movement quantity between the frames is detected.
In this method, even if the relative movement quantity between the frames is constant, it will be greatly influenced by the feature of the image (such as, for example, an image large in the structure variation or an image not varying so much in the structure/outline).
Needless to say, in most cases, it is desirable that, if the structure/outline part lags, the movement quantity will be detected to be large. However, it is desirable that a movement adapted to the use is detected.
Therefore, in a U.S. Pat. No. 4,779,131, it is disclosed that a movement is detected by accumulating difference values of corresponding pixels between different frames so that, in case the difference value is below a preset value, that pixel part will be considered to have no movement and the difference value will not be accumulated to elevate the reliability of the movement detection.
However, even if the difference value of the pixels between the frames is small, the movement quantity between both pixels will not be always small. For example, if both pixels represent parts having no ruggedness, even if a relative movement is present, it will not be able to be detected as a movement detection.
Also, in a U.S. Pat. No. 4,779,131, it is disclosed that a movement quantity is detected from a signal one frame before so that, in case the movement is large, a processed signal will be output. In a Japanese patent application laid open No. 106288/1985, the difference values of pixels near a luminance signal of both frames as well as the difference signals between the frames of the luminance signal are accumulated to determine the total sum of the movement quantities for all the pixels in both frames and the movement is detected by using this total sum of the movement quantities and the above mentioned difference signals between the frames.
In this prior art example, the circuit scale of the part of accumulating the difference values between the respective pixels of both frames and the pixels near the frames will become so large that the cost will be also high.